During mass production of electronic products and prior to assembly of a printed circuit board therein, a test operation conducted onto the printed circuit board plays a major role. The electrical contacts of a respective printed circuit board must under go a testing operation in order ensure the circuit operation thereof. Only after assuring that there is no short circuit in the printed circuit board, the assembly of the former is carried out.
FIG. 1 is a perspective view of a conventional test apparatus 1 in use presently in the assembly line. The test apparatus 1 accordingly includes a foundation 11, a base seat 12, an upper plate 13, a lower plate 14 and a coupler arm unit 15. The upper plate 13 is formed with four holding tubes 131, and has a plurality of probes 132. The lower plate 14 is formed with four retention inserts 141, and has a plurality of probes 142 respectively aligned with the probes 132 of the upper plate 13. The foundation 11 is equipped with a plurality of control units and circuit paths for establishing electrical communication the probes of the upper and lower plates 24, 22 via the coupling arm unit 15. A pneumatically operated piston unit serves as the control unit for moving the upper plate 13 with respect to the lower plate 14 so as to conduct the test operation thereof.
For carrying out the test operation, the printed circuit board under test is disposed above the lower plate 14, in which, the electrical contacts on one side of the printed circuit board are engaged with the probes 142 of the lower plate 14. The upper plate 13 is pressed downward via the coupling arm unit 15 toward the lower plate 14, in which, the retention inserts 141 of the lower plate 14 extend respectively into the holding tubes 131 of the upper plate 13. Under this condition, the electrical contacts on the other side of the printed circuit board are engaged with the probes 132 of the upper plate 13. The operator reads the test result with the assistance of corresponding software or programs.
Note that since the print circuit board under test is placed onto the lower plate manually by the operator, the same is subjected to shift from its initial position during the testing operation (i.e. since being pressed by the upper plate 13). The board displacement during the testing operation may result in misalignment between the probes of the upper and lower plate with respect to the electrical contacts of the printed circuit board, thereby causing bending of the printed circuit board, which, in turn, affects some components (such as Ball Grid Array) mounted thereon in addition the inaccurate test result and rupture at the soldering balls.